Carmela Panico owns seven so-called "bikini barista" coffee stands in Everett, Lynnwood, Kent and Edmonds. The 51-year-old was arrested in June and accused of promoting prostitution.
Since her arrest, detectives from the Everett Police Department have identified more than 100 of Panico's current or former employees.
During those interviews, police say they learned Panico was pressuring several of the women not to cooperate with the investigation.
She also singled out one potential witness and "applied pressure for her to change statements" she made to investigators, according to police.
Based on those interviews, police say they developed probable cause to arrest Panico on suspicion of three counts of tampering with a witness and a single count of intimidating a witness.
Panico announced in August that she's suing the City of Everett to recover $250,000 she says was wrongfully seized by police. The cash was seized in a search of her home in Snohomish.
The investigation is ongoing.